I'll work with our ops guys tomorrow to see what they find. They run Docker a lot.
I deleted and recreated dashboard and mongo containers and ran setup again (deleting the mongo container I think make it safe). The set portal domain now completes successfully, but now I get
"error": "There was a problem proxying the request"
and the log shows
tyk_gateway_1 | time="Feb 2 02:59:21" level=error msg="http: proxy error: dial tcp [::1]:3000: getsockopt: connection refused" api_id=dfe862e1b5e54cee7517603e65642be4 org_id=58929e6c43f478000117ac06 server_name="localhost:3000" user_id= user_ip=172.18.0.1 user_name=
so still no success.